Myotonic dystrophy


What is myotonic dystrophy?

Myotonic dystrophies (DM) are the most frequent muscular dystrophy in adulthood. They are thought to affect at least 1 in 8,000 people worldwide

Myotonic dystrophies are genetic disorders (relating to genes or heredity). They are multi-systemic conditions. This means they affect many systems in the body, not only the muscles.

The genetic change that causes myotonic dystrophy is present at birth, but symptoms may become noticeable at almost any age. Usually, the earlier the symptoms occur, the more severe the condition will be.

There are two types of myotonic dystrophy:

  • Myotonic dystrophy type 1 (DM1, also known as Steinert’s disease) 
  • Myotonic dystrophy type 2 (DM2) 

DM1 is the most common form of myotonic dystrophy and is often the most severe.

Myotonic dystrophies are multi-system diseases. They affect not only skeletal muscles (causing progressive muscle weakness and wasting) but also the following:

  • Energy levels and motivation
  • Body movement and balance
  • The heart: the heart conduction system (causing rhythm disturbances) and the heart muscle 
  • Breathing
  • Swallowing
  • Gut and bowels
  • Vision (i.e. cataracts)
  • Brain and cognition 
  • Body hormones
  • Muscle contractions and relaxation (i.e myotonia signs)
  • Sleep (Day-time sleepiness)

Myotonic dystrophy can affect these systems in different ways, and to different degrees of severity. This is the case even among people with the same subtype, and among family members.

 There is currently no cure for myotonic dystrophy but there are potential new treatment options on the horizon.  The general medical community often does not have a good understanding of myotonic dystrophy, as it is a rare disease. This lack of understanding of the condition can delay diagnosis and treatment. 

Last modified
31 October 2019